How to Attach Drywall to Plaster Walls

A long-handle drywall sander gives a smooth finish to drywall.

If the plaster walls in your home are unattractive or too costly to repair, you can cover them with drywall and start fresh. Drywall needs a sturdy substrate, so fasten loose plaster back to the wood lath strips behind it with plaster screws. Plaster screws have a washer-type fitting that helps prevent the plaster from cracking. Scrape any crumbled plaster off the lath and fill the resulting hollow with a patch of drywall. Once old plaster is stabilized, the walls are usually sound enough for new drywall.

1

Pry off the baseboards, window and door trim and crown molding in the room with the flat end of a pry bar. Number the back of each piece of trim to help you reinstall the pieces correctly.

2

3

Locate the wall studs behind the plaster with a stud finder. Stud finder operation differs slightly by manufacturer, but most are battery powered. As a stud finder is passed across a wall, the increased wall density that indicates a stud is signaled by lights or sounds from the stud finder. Following the manufacturer’s operating instructions, find the studs throughout the room and mark the locations at the bottom edge of the wall as close to the floor as possible. If removing the baseboards exposed part of the wall studs at the floor level, you don’t need to mark the studs on the wall.

4

Place a row of 1-inch-thick boards on the floor along the base of one wall. Transfer the stud locations from the wall straight down to the boards on the floor, marking the tops of the boards with a pencil. These boards are also spacers that create an expansion gap between the bottom edge of the drywall and the floor.

5

Set the first sheet of drywall against the wall and rest the bottom edge on top of the row of spacer boards.

6

Insert 2-inch drywall screws through the drywall and into the wall studs behind the plaster with a power drill and a Phillip's-head screwdriver bit. Use the stud marks on the spacer boards as a stud location guide. Space screws approximately 6 inches apart along every stud, but don’t insert screws closer than 3/4 inch from the edges of the drywall.

7

Hang the remainder of the drywall on the wall, leaving a 1/8-inch space between sheets, until you reach the end of the wall. As you approach an obstacle such as an outlet or light switch, measure and mark the location of the obstacle on the drywall and cut out the opening with a utility knife.

8

Pull out the spacer boards after the wall is complete, and move the boards to the next wall.

9

Scratch out the old stud location marks on the boards, make new stud marks as necessary, then continue hanging drywall around the room in the same manner.

Things You Will Need

Pry bar

Flat-head screwdriver

Stud finder

Pencil

Boards, 1 inch thick

Drywall screws, 2 inch

Power drill with Phillip's-head screwdriver bit

Tips

In some cases, plaster is much thicker than you realize. If 2-inch drywall screws don’t grab the studs behind the plaster, longer screws should do the trick.

Finish the drywall with drywall joint compound and seam tape as you would with any other drywall installation.

Reinstall the trim pieces in the same order that you removed them. In many cases, you will need to shorten a few of the baseboard and crown molding sections at the ends where they meet in corners. The additional thickness of drywall reduces the circumference of the room. Make these trim cuts with a miter saw, duplicating the angles of the original cuts.

Warnings

Use the thin drywall. Very thick drywall will likely require you to reposition the existing electrical boxes, called gang boxes, forward to bring the front edge flush with the drywall. With thinner drywall, you can usually loosen the screws on a receptacle by approximately 1/2 turn to move the receptacle forward slightly. If you are not comfortable working with electricity, hire an electrician to shut off the power before you begin working and to make necessary adjustments after you are finished installing the drywall.

Some installers hang drywall without removing the baseboards and the window and door trim. This type of installation, which butts against the trim instead of fitting behind it, is instantly recognizable as an improper shortcut. Trim molding should fit proud of the plane of the wall, not recess into it.

In many older homes with plaster walls, baseboards were custom milled for the house. Broken baseboards may be costly to replace, and require a professional millworker’s skill.

Consider the integrity of the plaster before hanging drywall over it. In most cases, plaster that is in good condition is a much harder and more stable wall material. In some cases, drywall is inappropriate for the period of the home. Plaster that only has a few cracks is easy to repair with a skim coat of finish plaster.

About the Author

Lee Carroll, a writer based in east Tennessee, has authored numerous law and DIY home improvement articles and essays. In addition to holding a degree in paralegal studies, she has more than 10 years of experience renovating newer homes and restoring historic property.